The hypotenuse is the side opposite the right angle in a right triangle. Each motif in this lightweight, shimmery scarf or rectangular shawl has three right triangles: a stockinette triangle, a reverse stockinette triangle, and a lace triangle (holey triangle, Batman!) … in theory anyway. In practice there are waves and curves instead of straight lines. The Merino Tencel Fingering yarn has a lovely drape, so the triangles seem to be draping as well.